title: Further characterization of Renibacterium salmoninarum extracellular products.
abstract: Renibacterium salmoninarum, the agent of bacterial kidney disease in salmonids, releases high concentrations of extracellular protein in tissues of infected fish. The extracellular protein consists almost entirely of a 57-kDa protein and derivatives of degradation and aggregation of the same molecule. The 57-kDa protein and its derivatives were fractionated into defined ranges of molecular mass. Separated fractions continued to produce degradation and aggregation products. One-dimensional electrophoretic separation of extracellular protein revealed a number of proteolytically active bands from > 100 to approximately 18 kDa associated with various 57-kDa protein derivatives in the different molecular mass fractions. Two-dimensional separation of extracellular protein showed that continued degradation and aggregation, similar both in location and behavior to some of the 57-kDa protein derivatives, was also displayed by the proteolytically active bands after their separation. Effects of reducing agents and sulfhydryl group proteinase inhibitors indicated a common mechanism for the proteolytically active polypeptides characteristic of a thiol proteinase. The results suggested that the 57-kDa protein and some of its derivatives undergo autolytic cleavage, releasing a proteolytically active polypeptide(s) of at least 18 kDa. Soluble polysaccharide-like material also was detected in extracellular products and tissue from infected fish. Antiserum to the polysaccharide-like material cross-reacted with O-polysaccharide of the fish pathogen Aeromonas salmonicida, suggesting some structural similarity between these polysaccharides. The polysaccharide and the proteolytic activity associated with the 57-kDa protein derivatives should be investigated with respect to the pathogenesis of R. salmoninarum infections.
authors.affiliation: Department of Biology, University of New Brunswick, Fredericton, Canada.
authors.forename: T A
authors.initials: TA
authors.lastname: Barton
authors.forename: L A
authors.initials: LA
authors.lastname: Bannister
authors.forename: S G
authors.initials: SG
authors.lastname: Griffiths
authors.forename: W H
authors.initials: WH
authors.lastname: Lynch
mesh_terms: D000333:Aeromonas / Q000276:immunology; D000818:Animals; D001426:Bacterial Proteins / Q000737:chemistry / Q000276:immunology / Q000378:metabolism; D003429:Cross Reactions; D010450:Endopeptidases / Q000378:metabolism; D005110:Extracellular Space / Q000378:metabolism; D005393:Fish Diseases / Q000209:etiology; D006094:Gram-Positive Bacteria / Q000276:immunology / Q000378:metabolism* / Q000472:pathogenicity; D016908:Gram-Positive Bacterial Infections / Q000209:etiology / Q000662:veterinary; D007674:Kidney Diseases / Q000209:etiology / Q000662:veterinary; D008970:Molecular Weight; D011135:Polysaccharides, Bacterial / Q000737:chemistry / Q000276:immunology / Q000378:metabolism; D012487:Salmonidae / Q000382:microbiology; D014774:Virulence
chemical_list: D001426:Bacterial Proteins; D011135:Polysaccharides, Bacterial; D010450:Endopeptidases